Lettuce同步命令源码分析

    public StatefulRedisConnectionImpl(RedisChannelWriter writer, RedisCodec<K, V> codec, Duration timeout) {

        super(writer, timeout);

        this.codec = codec;
        //创建异步redis命令处理模式
        this.async = newRedisAsyncCommandsImpl();
        //创建redis命令同步处理模式
        this.sync = newRedisSyncCommandsImpl();
        //创建redis命令响应式处理模式
        this.reactive = newRedisReactiveCommandsImpl();
    }

protected RedisCommands<K, V> newRedisSyncCommandsImpl() {
        return syncHandler(async(), RedisCommands.class, RedisClusterCommands.class);
    }

protected <T> T syncHandler(Object asyncApi, Class<?>... interfaces) {
        //对异步API创建调用处理器
        FutureSyncInvocationHandler h = new FutureSyncInvocationHandler((StatefulConnection<?, ?>) this, asyncApi, interfaces);
        //创建动态代理
        return (T) Proxy.newProxyInstance(AbstractRedisClient.class.getClassLoader(), interfaces, h);
    }

 public final Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //如果参数为null则 将args设置为"{}"
        if (args == null) {
            args = NO_ARGS;
        }
        //如果参数长度为0同时方法名称为hashCode则直接返回hashCode
        if (args.length == 0 && method.getName().equals("hashCode")) {
            return hashCode();
        }
        //如果是equals
        if (args.length == 1 && method.getName().equals("equals") && method.getParameterTypes()[0] == Object.class) {
            Object arg = args[0];
            if (arg == null) {
                return false;
            }
            if (proxy == arg) {
                return true;
            }
            return isProxyOfSameInterfaces(arg, proxy.getClass()) && equals(Proxy.getInvocationHandler(arg));
        }
        //如果是toString
        if (args.length == 0 && method.getName().equals("toString")) {
            return toString();
        }
        return handleInvocation(proxy, method, args);
    }

 protected Object handleInvocation(Object proxy, Method method, Object[] args) throws Throwable {

        try {
            //获取当前method在asyncApi 中对应的方法
            Method targetMethod = this.translator.get(method);
            //调用异步接口
            Object result = targetMethod.invoke(asyncApi, args);
            //如果返回结果是RedisFuture类型
            if (result instanceof RedisFuture<?>) {
               //类型强转
                RedisFuture<?> command = (RedisFuture<?>) result;
                  //如果不是事务控制方法 同时还在事务中则返回null
                if (isNonTxControlMethod(method.getName()) && isTransactionActive(connection)) {
                    return null;
                }
                //是事务控制方法，或不在事务中则进行如下处理
                //等待超时或取消
                LettuceFutures.awaitOrCancel(command, connection.getTimeout().toNanos(), TimeUnit.NANOSECONDS);
               //返回结果,这里处理不是很好 上一步中就可以直接返回了
                return command.get();
            }
            //如果不是RedisFuture类型则直接返回
            return result;
        } catch (InvocationTargetException e) {
            throw e.getTargetException();
        }
    }

/**
     * 方法翻译器
     */
    protected static class MethodTranslator {

        private final static WeakHashMap<Class<?>, MethodTranslator> TRANSLATOR_MAP = new WeakHashMap<>(32);
        
        //真实方法和代理类中方法映射表
        private final Map<Method, Method> map;

        private MethodTranslator(Class<?> delegate, Class<?>... methodSources) {

            map = createMethodMap(delegate, methodSources);
        }

        /**
         * 通过指定代理类，和目标类创建方法翻译器
         */
        public static MethodTranslator of(Class<?> delegate, Class<?>... methodSources) {
            //同步代码块
            synchronized (TRANSLATOR_MAP) {
                //如果翻译器映射表中不存在delegate的翻译器则创建一个新的
                return TRANSLATOR_MAP.computeIfAbsent(delegate, key -> new MethodTranslator(key, methodSources));
            }
        }

        private Map<Method, Method> createMethodMap(Class<?> delegate, Class<?>[] methodSources) {

            Map<Method, Method> map;
            List<Method> methods = new ArrayList<>();
            //遍历源类，找到所有public方法
            for (Class<?> sourceClass : methodSources) {
                methods.addAll(getMethods(sourceClass));
            }

            map = new HashMap<>(methods.size(), 1.0f);

            //创建方法和代理类的方法的映射表
            for (Method method : methods) {

                try {
                    map.put(method, delegate.getMethod(method.getName(), method.getParameterTypes()));
                } catch (NoSuchMethodException ignore) {
                }
            }
            return map;
        }
       //获取目标方法中的所有方法
        private Collection<? extends Method> getMethods(Class<?> sourceClass) {

            //目标方法集合
            Set<Method> result = new HashSet<>();

            Class<?> searchType = sourceClass;
            while (searchType != null && searchType != Object.class) {
                 //将目标类中所有public方法添加到集合中
                result.addAll(filterPublicMethods(Arrays.asList(sourceClass.getDeclaredMethods())));
                //如果souceClass是接口类型
                if (sourceClass.isInterface()) {
                    //获取souceClass的所有接口
                    Class<?>[] interfaces = sourceClass.getInterfaces();
                    //遍历接口，将接口的public方法也添加到方法集合中
                    for (Class<?> interfaceClass : interfaces) {
                        result.addAll(getMethods(interfaceClass));
                    }

                    searchType = null;
                } else {//如果不是接口则查找父类

                    searchType = searchType.getSuperclass();
                }
            }

            return result;
        }

        //获取给定方法集合中所有public方法
        private Collection<? extends Method> filterPublicMethods(List<Method> methods) {
            List<Method> result = new ArrayList<>(methods.size());

            for (Method method : methods) {
                if (Modifier.isPublic(method.getModifiers())) {
                    result.add(method);
                }
            }

            return result;
        }

        public Method get(Method key) {
           //从方法映射表中获取目标方法
            Method result = map.get(key);
            //如果目标方法不为null则返回,否则抛出异常
            if (result != null) {
                return result;
            }
            throw new IllegalStateException("Cannot find source method " + key);
        }
    }
}